Line concentrator service observing circuit



p 1 7 M. E. KROM ET AL 02,668

LINE CONCENTRATOR SERVICE OBSERVING CIRCUIT Filed Oct. 4, 1955 19 Sheets-Sheet 1 TRUNK car no TkUN/f CCT. /7'9 Ar. E. KROM lNl/E/VTORS M.

A TTORNEV FIG! Sept, 24, 1957 M. E. KROM ET AL LINE CONCENTRATOR SERVICE OBSERVING CIRCUIT l9 Sheets-Sheet 2 Filed Oct. 4. 1955 kvum ' MI 'E. mom

/NVENTOR$ M. POSl/V ATTORNEY Sept. 24, 1957 M. E. KROM ET AL 19 Sheets-Sheet 3 09 QORWWKEMUEDU M. E. KROM lNl/ENTORS M BY 7 ATTORNEY Sept. 24, 1957 M. E. KROM ETAL LINE CONCENTRATOR SERVICE OBSERVING CIRCUIT Filed Oct. 4, 1955 19 Sheets-Sheet 4 66v RSUQG QMKMEYE Q21 030mb QMQQD? M. E. "KROM M. POS/N INVENfORS v at M. E. KROM ET AL Sept. 24, 1957 LINE CONCENTRATOR SERVICE OBSERVING CIRCUIT l9 Sheets-Sheet 5 Filed Oct. 4, 1955 M. E. KROM wvavrops M Pas/N B'V h ATTORNEY M. E. KROM ET AL Sept, 24, 1957 19 Sheets-Sheet 6 06 QORYGREMURDU M. E. KROM INVENTORS. M Pas/N ATTORNEY Sept. 24, 1957 M. E. KROM ET AL 2,807,668

LINE CONCENTRATOR SERVICE OBSERVING CIRCUIT Filed Oct. 4, 1955 19 Sheets-Sheet '7 035mm T/ON co/v TROL C/RCU/T A T TORNE V Sept. 24, 1957 M. E. KROM ET AL 2,807,668

LINE CONCENTRATOR SERVICE OBSERVING CIRCUIT Filed Oct. 4, 1955 19 Sheets-Sheet a llll Hll TRA SFER C/RCU/ T COMMON CONTROL C IRC U 7' A TTOPNE? .Sept. 24, 1957 M. E. KROM ET AL 2,807,658

LINE CONCENTRATOR SERVICE OBSERVING CIRCUIT Filed Oct. 4, 1955 19 Sheets-Sheet 9 A T TOPA Fy Sept. 24, 1957 M. E. KROM ETAL LINE CONCENTRATOR SERVICE OBSERVING CIRCUIT l9 Sheets-Sheet 10 Filed Oct. 4, 1955 M. E. KROM wvewrom M Pas/N B! p A TTORNE V Sept. 24, 1957 M. E. KROM ETAL 2,807,668

' LINE CONCENTRATOR SERVICE OBSERVING CIRCUIT Filed Oct. 4, 1955 l9 Sheets-Sheet ll SIGNAL CC 7'. H5760)- M. E M mag/Tom Pas/N ATTORNEY FIG.

Sept. 24, 1957 M. E. KROM ETAL LINE CONCENTRATOR SERVICE OBSERVING CIRCUIT Filed Oct. 4, 1955 19 Sheets-Sheet 12 mum mwk i Nun $453M ME. mou M. Pas/ 1v INVENTORS:

ATTORNEY Sept. 24, 1957 M. E. KROM ETAL 2,807,663

LINE CONCENTRATOR SERVICE OBSERVING CIRCUIT Filed Oct. 4, 1955 I 19 Sheets-Sheet 13 L a l I TRUNK CONTROL C C T. I300 .M. E, KROM lNVEA/TORS Pas/N ATTORNEY la. /.3' I

Sept. 24, 1957 M. E. KROM ET AL 2,807,668

LINE CONCENTRATOR SERVICE OBSERVING CIRCUIT Filed Oct. 4, 1955 19 Sheets-Sheet 14 M. E. lA/l/E/VTORS. M Pas/N A T TOPNFY Sept. 24, 1957 M. E. KROM ETAL ,80

LINE CONCENTRATOR SERVICE OBSERVING CIRCUIT Filed Oct. 4, 1955 19 Sheets-Sheet 16 TRANSLA TOR CC 7. 600

ME. KROM INVENTOPS A 7' TOR/V5 V 19 Sheets-Sheet 18 M. E. KROM ETAL ME. KROM M. POS/N Sept. 24, 1957 LINE CONCENTRATOR SERVICE OBSERVING CIRCUIT Filed Oct. 4, 1955 INVENTORS Q not A TTORNEV Unite LINE CONCENTRATDR SERVICE OBSERVING CIRCUIT Application October 4, 1955, Serial No. 538,335

18 Claims. Cl. 179-18) This invention relates to telephone service observation equipment and more particularly to service observing circuits for line concentrator telephone systems.

Occasionally a telephone subscriber will register a complaint or inquiry concerning the nature of the service provided. The substance of complaints embraces almost the entire range of telephone service, and includes such items as wrong numbers, dont answer calls, overcharges and'various other occurrences generally based upon some improper use of the calling device, or faulty performance of the telephone line or central office equipment. It becomes necessary, therefore, when a subscriber complains, to-determine from an actual observation of the subscribers line whether poor service is actually being rendered and, if so, to determine the cause. In order for the observation operator to observe, monitor, or supervise the operation of the switching equipment involved in theparticular subscribers line responsive to the origination of a call thereon, the operator must receive an indication of the origination of a call on the line and must be provided with a bridgingtalking connection across the line. When the subscribers line terminates at, or is connected directly to, the central office, the provision of such indication and connection is a relatively simple matter. However, in concentrator telephone systems, for example, of the type describedin our copending applications Serial No. 538,- 333 and Serial No. 538,334, filed on even date herewith, the subscriber lines terminate in line concentrators which are each connected by relatively few concentrator trunks to the central ofiice. The central oflice is therefore not directly in information communication with the subscriber lines due to the interposition of the remote line concentrators.

It is ,a general object of this invention to provide line observation facilities for subscriber lines in a linev concentrator telephone system.

In order to accomplish this and other objects, an indication of the origination of a call on the observed line must be provided to the observation operator. The indication must be provided before the operation of the central office switching equipment which is involved in connecting the subscriber line to the central office through the line concentrator and one of the concentrator trunks. One of the important features of the present invention resides in the provision of means for accomplishing this objective. The means include an observation trunk which is connectable at the line concentrator to any one of the subscriber lines, and which is connected at the central office to an observation control circuit. The observation control circuit functions in conjunction with a common control circuit, also at the central ofiice, to control the line concentrators in establishing a connection between the line to be observed and the observation trunk. Thev common control circuit is also utilized in establishing connections between the subscriber lines and the concentrator trunks which connect the concentrators to the central ofiice.

When a call is originated on the observed line, an in- States Patent 2 dication thereof is provided over the observation trunk, before signals representing the identity of the calling line are supplied to the central office for initiating the operation of the common control circuit. Such signals are necessary because the central ofiice is not directly in information communication with the subscriber lines, due to the interposition of the line concentrator. The origination indication readies the observation control circuit. The control circuit provides a connection from a service observing jack to the talking'trunk which is selected and utilized for the call. When the common control circuit functions to establish a connection at the concentrator between the calling line and a selected one of the concentrator trunks, it also operates the readied observation control circuit. The observation control circuit releases the observation trunk circuit at the concentrator, and establishes a connection in the central ofiice between the selected concentrator trunk and the service observing jack in the observation control circuit.

A feature of the present invention relates to the provision of the service observation connection at the central oflice from the service observing jack to the selected concentrator trunk while releasing the observation trunk circuit. The observation trunk circuit is released in order to avoid the transmission losses due to bridging the observed line by the observation trunk when a concentrator trunk is connected thereto. The observation trunk is never connected to the observed line at the same time that a concentrator trunk is connected thereto. I

Another feature of the present invention resides in the utilization of the concentrator signaling means at the central office for the service observing function. Essentially the same signaling equipment at the central office, and signal receiving, or number group equipment, in the concentrator are utilized for the service observing function and for all types of calls.

A further feature of the present invention is the provision of an observation control circuit which can be utilized for a line terminating at any one of a plurality of line concentrators.

7 Further objects and features will become apparent to those skilled in the art upon consideration of the following description read in conjunction with the drawing wherein:

Figs. 1 through 16, when arranged in accordance with Fig. 17, are circuit representations of the lines concentrator and service observing equipment of the present invention wherein: I

Fig. 1 illustrates the concentrator trunk circuits;

Fig. 2 illustrates the concentrator line circuit and line lockout and identifying circuit; 7 r 1 Fig.- 3 illustrates the concentrator observation trunk circuit; Fig. 4 illustrates the concentrator number group and transfer circuit;

Fig. 5 illustrates the concentrator translator circuit;

Fig. 6 illustrates diagrammatically another concentrator;

Fig. 7 illustrates the observation control circuit in the central office;

Figs. 8, 9 and 10 illustrate the transfer circuits and the common control circuit in the central office;

Figs. 11 and 12 illustrate a signal circuit in the central oflice;

Fig. 13 illustrates diagrammatically another signal circuit in the central office;

Fig. 14 illustrates a timing and connector circuit in the central oifice; I

Fig. 15 illustrates diagrammatically some of the'components in a No. 5 crossbar telephone system;

Fig. 16 illustrates a translator circuit in the central oflice; 

